Various conventional split hexalobe driver devices exist for retaining and rotating locking caps, set screws, and bone screws used in orthopedic surgical procedures and the like. These driver devices typically include a handle portion, an elongate shaft portion, and an end portion that includes a screw engagement portion and a split manufactured down the central axis of the end portion and/or the screw engagement portion, forming two symmetric halves of the end portion and/or screw engagement portion. This screw engagement portion is slightly oversized relative to the corresponding tool engagement recess of the locking cap, set screw, or bone screw. Thus, when the screw engagement portion is pressed into the corresponding tool engagement recess of the locking cap, set screw, or bone screw, the split manufactured down the central axis of the end portion and/or the screw engagement portion allows the screw engagement portion to compress slightly, creating a friction fit between the screw engagement portion and the corresponding tool engagement recess of the locking cap, set screw, or bone screw. As a result, the locking cap, set screw, or bone screw is retained by the screw engagement portion prior to and while being rotated.
Because the split is manufactured down the central axis of the end portion and/or the screw engagement portion and two symmetric halves of the end portion and/or screw engagement portion are formed, when the driver device and locking cap, set screw, or bone screw are rotated, the two symmetric halves of the end portion and/or screw engagement portion do not have sufficient strength to resist the torque applied to them, the two symmetric halves of the end portion and/or screw engagement portion twist and/or otherwise deform slightly, and the driver device fails to effectively and/or adequately rotate the locking cap, set screw, or bone screw. Thus, what is still needed in the art is an improved driver device that avoids this problem.